The following priorities have been set for waste management at Evonik:
- The first priority is to avoid waste through continuous process improvements and by extending integrated production systems,
- If this is not possible, waste should be recycled or used to generate energy, and
- as a last resort, it should be disposed of safely.
We use catalysts to increase yields and reduce side reactions. Integrated material flows also make a contribution. The benefits of integrated production sites and systems are also used for systematic waste management, for example in Marl (Germany), which is our largest site. Here, hydrocarbon residues are used as a substitute for heating oil in the synthesis gas plant, and waste sulfuric acid in the sulfuric acid plant is reprocessed. Sewage sludge can also be reused within the integrated production structure. Dewatering is followed by thermal reprocessing by incinerating it in a separate incineration plant with integrated flue gas treatment. Some of the exhaust gases from the production plants are used as substitute fuels in this process. The incineration gases are then used to generate 20 bar steam. To conserve resources, at many of our sites we use substitute fuels such as liquid residues from production processes.